Selected 100 unrelated individuals with farmer's lung. Select two healthy control groups of 100 individuals each who have similar exposure but no precipitating antibodies and who have similar exposure with presence of precipitating antibodies. Select 100 unrelated individuals with alternaria induced asthma. Select 100 unrelated individuals with allergic aspergillosis. Select three control groups for comparison with above groups. Carry out tissue typing and collect and process data.